1. Technical Field
The present invention relates to buffered distributors, more specifically to full-duplex buffered distributors sending data packets between network nodes.
2. Background Art
Repeaters are typically used as an interconnection between network nodes, for example network stations serving as data terminal equipment (DTE) on different network media. Repeaters provide the advantage of extending the physical distance between network nodes by receiving the data packet from one network media, reconditioning the physical signal, and outputting the data packet to a second network media.
Certain vendors have proposed a buffered distributor, also referred to as a full-duplex repeater, as a viable alternative to a half-duplex repeater. Specifically, the buffered distributor includes a number of network ports, where each network port is configured for full-duplex communication with a corresponding network node. Each network port includes a receive first in-first out (FIFO) buffer, and a transmit FIFO buffer. The buffered distributor also includes a repeater core, also referred to as a "backplane," that distributes a data packet stored in one of the receive FIFO buffers to the other network ports. Specifically, a receive FIFO buffer outputs a stored data packet to the other network ports by gaining access to the backplane. Access to the backplane may be implemented either by CSMA/CD logic, where the Receive FIFO buffers contend for access to the backplane using a zero topology collision domain (using CSMA/CD logic), or another arbitration scheme such as round-robin.
The above-described buffered distributor also includes a flow control mechanism according to IEEE 802.3x, where the repeater core will generate a PAUSE frame when a predefined threshold is reached in the one of the receive FIFO buffers. Specifically, a network port having a detected congestion condition (i.e., stored data exceeding the predefined threshold) in its corresponding receive FIFO buffer will output a MAC control frame carrying a predetermined PAUSE interval into the corresponding transmit FIFO buffer. The network node in communication with that network port, having received the MAC control frame, will suspend transmission for the predetermined PAUSE interval, enabling the repeater core to remove packet data from the congested receive FIFO buffer.
A problem encountered in use of a buffered distributor in a workgroup environment is that one or more servers may be connected to the buffered distributor along with several clients. In addition, one of the ports may be connected to a router or switch. In such an environment, the router port (or switch port) will see all the frames that are communicated between the client and the server. Hence, the router port (or switch port) may be unnecessarily used to transmit non-relevant traffic to the router (or switch). Moreover, resources in the router (or switch) are wasted in reading and discarding the received data frames that are intended for the client and server.